1 /*- 2 * Copyright (c) 2013 The FreeBSD Foundation 3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer 15 * in this position and unchanged. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 * 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include <sys/param.h> 37 #include <sys/kernel.h> 38 #include <sys/lock.h> 39 #include <sys/malloc.h> 40 #include <sys/module.h> 41 #include <sys/random.h> 42 #include <sys/selinfo.h> 43 #include <sys/systm.h> 44 45 #include <machine/md_var.h> 46 #include <machine/specialreg.h> 47 48 #include <dev/random/randomdev.h> 49 #include <dev/random/randomdev_soft.h> 50 #include <dev/random/random_harvestq.h> 51 #include <dev/random/live_entropy_sources.h> 52 #include <dev/random/random_adaptors.h> 53 54 #define RETRY_COUNT 10 55 56 static int random_ivy_read(void *, int); 57 58 static struct random_hardware_source random_ivy = { 59 .ident = "Hardware, Intel IvyBridge+ RNG", 60 .source = RANDOM_PURE_RDRAND, 61 .read = random_ivy_read 62 }; 63 64 static inline int 65 ivy_rng_store(long *buf) 66 { 67 #ifdef __GNUCLIKE_ASM 68 long tmp; 69 int retry; 70 71 retry = RETRY_COUNT; 72 __asm __volatile( 73 "1:\n\t" 74 "rdrand %2\n\t" /* read randomness into tmp */ 75 "jb 2f\n\t" /* CF is set on success, exit retry loop */ 76 "dec %0\n\t" /* otherwise, retry-- */ 77 "jne 1b\n\t" /* and loop if retries are not exhausted */ 78 "jmp 3f\n" /* failure, retry is 0, used as return value */ 79 "2:\n\t" 80 "mov %2,%1\n\t" /* *buf = tmp */ 81 "3:" 82 : "+q" (retry), "=m" (*buf), "=q" (tmp) : : "cc"); 83 return (retry); 84 #else /* __GNUCLIKE_ASM */ 85 return (0); 86 #endif 87 } 88 89 static int 90 random_ivy_read(void *buf, int c) 91 { 92 long *b; 93 int count; 94 95 KASSERT(c % sizeof(long) == 0, ("partial read %d", c)); 96 for (b = buf, count = c; count > 0; count -= sizeof(long), b++) { 97 if (ivy_rng_store(b) == 0) 98 break; 99 } 100 return (c - count); 101 } 102 103 static int 104 rdrand_modevent(module_t mod, int type, void *unused) 105 { 106 int error = 0; 107 108 switch (type) { 109 case MOD_LOAD: 110 if (cpu_feature2 & CPUID2_RDRAND) 111 live_entropy_source_register(&random_ivy); 112 else 113 #ifndef KLD_MODULE 114 if (bootverbose) 115 #endif 116 printf("%s: RDRAND is not present\n", 117 random_ivy.ident); 118 break; 119 120 case MOD_UNLOAD: 121 if (cpu_feature2 & CPUID2_RDRAND) 122 live_entropy_source_deregister(&random_ivy); 123 break; 124 125 case MOD_SHUTDOWN: 126 break; 127 128 default: 129 error = EOPNOTSUPP; 130 break; 131 132 } 133 134 return (error); 135 } 136 137 LIVE_ENTROPY_SRC_MODULE(random_rdrand, rdrand_modevent, 1); 138